Volume limiting ventilators have heretofore been provided as, for example, disclosed in U.S. Pat. Nos. 3,530,856 and 4,020,834. However, there is a need to provide an updated volume limiting ventilator providing additional features such as selectable nebulization, failsafe devices and other features normally associated with non-volume limiting ventilators. There is, therefore, a need for a new and improved volume limiting ventilator.